/* 
接口可以描述函数类型
限定函数的参数和返回值的类型
*/
interface searchFnInter {
  (x: string, y: string): boolean
}
const searchFn: searchFnInter = (a: string, b: string) => {
  return a.includes(b)
}
console.log(searchFn('abcd', 'bc'))